1. Field of the Invention
The present invention relates to a support base-attached encapsulant, an encapsulated substrate having semiconductor devices mounted thereon or an encapsulated wafer having semiconductor devices formed thereon using the encapsulant, a semiconductor apparatus manufactured from these, and a method for manufacturing the semiconductor apparatus.
2. Description of the Related Art
In the field of semiconductor apparatus production, various methods have been conventionally investigated about wafer-level encapsulation for a semiconductor device mounting surface of a substrate having semiconductor devices mounted thereon or a semiconductor device forming surface of a wafer having semiconductor devices formed thereon, and there may be exemplified by a method of encapsulating by spin coating or screen printing (Patent Document 1), and a method of using a complex sheet where a heat fusible epoxy resin has been coated on a film-form support (Patent Document 2 and Patent Document 3).
According to the methods mentioned above, encapsulation can be done without any big problems when a small-diameter wafer or a small-area substrate such as organic, inorganic, or metal substrate with a size of about 200 mm (8 inches) is used. However, when a large-area substrate or a large-diameter wafer of 300 mm (12 inches) or more is to be encapsulated, there is a problem that the substrate or the wafer occasionally warps due to shrinkage stress of the epoxy resin, etc., at the time of encapsulating and curing, and especially, the large-diameter wafer with thin thickness is liable to warp. In addition, when a semiconductor device mounting surface of a large-area substrate having semiconductor devices mounted thereon is encapsulated, the problem occurs that the semiconductor devices are peeled from the substrate by shrinkage stress of the epoxy resin, etc., at the time of encapsulating and curing. Accordingly, there is a big problem that encapsulated large-area substrates and large-diameter wafers cannot be used for mass-production.
To solve the problems brought by increasing the area of the substrate having semiconductor devices mounted thereon or the wafer having semiconductor devices formed thereon, methods of blending a filler with a content of about 90% by mass into a resin composition for use in encapsulating, or lowering elasticity of the encapsulating resin composition thereby reducing the shrinkage stress at the time of curing have been proposed (Patent Documents 1, 2, and 3).
However, there newly arises a problem that, when about 90% by mass of the filler is blended, viscosity of the encapsulating resin composition increases, and force is applied to the semiconductor devices mounted on the substrate at the time of casting, molding, and encapsulating the encapsulating resin composition, whereby the semiconductor devices are peeled from the substrate. Moreover, when elasticity of the encapsulating resin is lowered, although warp of the encapsulated substrate having semiconductor devices mounted thereon or the encapsulated wafer having semiconductor devices formed thereon can be improved, reduction in reliability such as heat resistance and moisture resistance newly occurs. Therefore, these solving methods cannot provide fundamental solutions for the problems of the encapsulation of a large-area substrate or a large-diameter wafer.
There is an attempt to encapsulate a large-diameter wafer or a large-area substrate such as organic, inorganic, or metal substrate by using a substrate-attached encapsulant in which a resin layer for use in encapsulating is formed on a substrate such as a fiber-containing substrate (Patent Documents 4 and 5). In the fiber-containing substrate, low expansion coefficient tends to be required, and therefore, a substrate obtained by impregnating a fiber such as glass fiber with an organic resin composition highly filled with an inorganic filler is adopted in many cases. However, there is a problem that since the organic resin composition has high viscosity, force is applied to the glass fiber thereby causing opening or tangle of fiber, and consequently, uniformity and homogeneity of the substrate are lowered, and the package warps due to the internal stress. Moreover, since the fiber-containing substrate is molded by high-temperature vacuum pressing or the like after impregnating with the organic resin composition, it is inferior in productivity. Further, if the fiber-containing substrate is made thick in order to reduce fiber-opening, tangle, warp, etc., the final product after packaging disadvantageously becomes a tall component.
Accordingly, there has been demanded an encapsulant that can collectively encapsulate a semiconductor device mounting surface of a substrate having the semiconductor devices mounted thereon or a semiconductor device forming surface of a wafer having semiconductor devices formed thereon on a wafer level without occurrence of warp of the substrate or the wafer and peeling of the semiconductor devices from the substrate such as inorganic, organic, or metal substrate even when a large-diameter wafer or a large-area substrate such as inorganic, organic, or metal substrate is encapsulated, and that has uniformity and homogeneity without opening or tangle of fiber even when a thin substrate is used, and that is excellent in reliability such as heat resistance, electrical insulation property, and moisture resistance after encapsulating, and further excellent in versatility, economical efficiency, and mass-productivity.